'use strict'
// + 仅选择JavaScript
// var selected = null;
// selected = $('#para-1');

// + 仅选择Erlang
// var selected = null;
// selected = $('.color-red.color-green') ;

// + 选择JavaScript和Erlang
// var selected = null;
// selected = $('p[class^=color-red]')

// + 选择所有编程语言
// var selected = null;
// selected = $('p[class^=color]')

// + 选择名字input
// var selected = null;
// selected = $('input[name=name]')

// + 选择邮件和名字input
// var selected = null;
// selected = $('input[type!=password]')

if (!(selected instanceof jQuery)) {
    console.log(selected);
    console.log('不是有效的jQuery对象!');
}
$('#test-jquery').find('*').css('background-color', '');
selected.css('background-color', '#ffd351');